Operation

Standard Mode

In Standard mode, the SCR reheat operates only when the Temperature Proportional Band calls for heating. SCR reheat output is adjusted proportionally as the Temperature Proportional Band varies the requirement for heating from 0% to -100%. Compressors operate only when there is a call for cool- ing as described in 3.3.2 - Compressor Control.

Figure 21 illustrates how SCR reheat operates when SCR Control Type is set to Standard mode.

Figure 21 Two single-step compressors with SCR reheat set to Standard mode

Temp Setpoint: 70°F

 

Cool 2

Proportional Band : 8°F

Cool 1

On

Deadband : 0°F

On

 

 

 

 

SCR

 

 

On

 

66

67

68

69

70

71

72

73

74

-100%

0%

 

100%

Heating

Cool 1 Off

Cool 2

Cooling

 

SCR Off

Off

 

½ Proportional Band

½ Proportional Band

SCR On

Cooling 1 On

Cooling 2 On

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Image 32
Emerson iCOM user manual Standard Mode